Aqueous Ozonation Of Fatty Acids

The reactivity of a series of fatty acids toward ozone was examined in aqueous solution at low substrate concentration (μg.L^?1 range). Saturated fatty acids were unreactive, unsaturated fatty acids were readily consumed. A number of reaction products or their methylated derivatives were identified by gas chromatography and gas chromatography-mass spectrometry. The products identified are consistent with a 1,3-dipolar cyclo-addotion reaction.     

Metallurgical characterization of Ti-bearing 9Cr low activation martensitic steel

Two heats of low activation martensitic (LAM) steels with Ti and Ta (denominated as 9Cr-Ti and 9Cr-Ta),respectively,developed as candidate structure materials for nuclear reactor were characterized.This paper was focused on the effect of titanium on the microstructures and mechanical properties of 9Cr LAM steel in as-received condition (normalized at 950 ℃ for 30 min with water quenching plus tempered at 780 ℃ for 90 min with air cooling).Chemical analysis and microstructure observation were conducted on 9Cr-Ti and 9Cr-Ta with optical microscopy,X-ray diffraction analysis,scanning electron microscopy and transmission electron microscopy.Impact properties and tensile strengths were measured with Charpy impact experiments and tensile tests.The results indicated that 9Cr-Ti and 9Cr-Ta were fully martensitic steels in as-received condition.MX type and M23C6 type precipitates were observed distributing along boundaries of prior austenite grains and martensite laths in 9Cr-Ti.The addition of titanium accelerated the precipitation of TiC and TiN,and produced much finer grains in 9Cr-Ti than 9Cr-Ta at the same normalization temperature.Mechanical properties tests showed the ductile brittle transition temperatures of 9CrTi and 9Cr-Ta were about-90 ℃ and-85 ℃,respectively.The ultimate tensile strengths at room temperature and 600 ℃ were 680 MPa and 365 MPa for 9Cr-Ti,and 660 MPa and 335 MPa for 9Cr-Ta,respectively.The favorite impact toughness and tensile properties of 9Cr-Ti could be attributed to the fine grains in as-received condition.     

放电等离子烧结工艺对Ca3Co4O9陶瓷织构及电性能的影响

采用溶胶-凝胶与放电等离子烧结(SPS)相结合的方法制备了Ca3Co4O9陶瓷.通过X射线衍射、扫描电镜等表征手段,研究了放电等离子烧结工艺对Ca3Co4O9物相、显微结构和性能的影响.实验结果表明片状颗粒和放电等离子烧结工艺,特别是烧结温度的提高有利于Ca3Co4O9织构的形成.初步认为是片状颗粒在脉冲电流所产生的脉冲磁场作用下发生重排,使颗粒定向排列.本实验范围内,当烧结温度从700℃提高到900℃时,Ca3Co4O9晶粒取向度从0.75增大到0.87,700℃下的电阻率从6.24×10-5 Ωm降低到5.59×10-5 Ωm.此外,Ca3Co4O9块体表现出典型的半导体电学特征,电导率随着SPS烧结温度和测量温度的升高而增大,当SPS烧结温度为850℃时,P型Ca3Co4O9化合物在700℃有最大电导率.     

Oxidation mechanism of a Fe-9Cr-1Mo steel by liquid Pb-Bi eutectic alloy (Part I)

This paper is the first part of a global study on the oxidation process of a Fe-9Cr-1Mo martensitic steel (T91) in static liquid Pb-Bi. It focuses on the oxygen transport mode across the oxide scale. The oxide layer has a duplex structure composed of an internal Fe-Cr spinel layer and an external magnetite layer. Oxygen 18 tracer experiments are performed: they show that the magnetite layer grows at the Pb-Bi/ oxide interface whereas the Fe-Cr spinel layer grows at the metal/oxide interface. Oxygen seems to diffuse across the oxide scale dissolved inside nanometric lead penetrations called nano-channels. Specific experiments are performed to characterize the nano-channels.     

Role of Liver X Receptor,Insulin and Peroxisome Proliferator Activated Receptor α on in Vivo Desaturase Modulation of Unsaturated Fatty Acid Biosynthesis

We examined the in vivo contribution of insulin, T090137 (T09), agonist of liver X receptor (LXR), fenofibrate, agonist of peroxisome proliferator activated receptor (PPAR-α) and sterol regulatory element binding protein-1c (SREBP-1c) on the unsaturated fatty acid synthesis controlled by Δ6 and Δ5 desaturases, compared with the effects on stearoylcoenzyme A desaturase-1. When possible they were checked at three levels: messenger RNA (mRNA), desaturase protein and enzymatic activity. In control rats, only fenofibrate increased the insulinemia that was maintained by the simultaneous administration of T09, but this increase has no specific effect on desaturase activity. T09 enhanced SREBP-1 in control animals and the mRNAs and activity of the three desaturases in control and type-1 diabetic rats, demonstrating a LXR/SREBP-1-mediated activation independent of insulin. However, simultaneous administration of insulin and T09 to diabetic rats led to a several-fold increase of the mRNAs of the desaturases, suggesting a strong synergic effect between insulin and LXR/retinoic X receptor (RXR). Moreover, this demonstrates the existence of an interaction between unsaturated fatty acids and cholesterol metabolism performed by the insulin/SREBP-1c system and LXR/RXR. PPAR-α also increased the expression and activity of the three desaturases independently of the insulinemia since it was equivalently evoked in streptozotocin diabetic rats. Besides, PPAR-α increased the palmitoylcoenzyme A elongase, evidencing a dual regulation in the fatty acid biosynthesis at the level of desaturases and elongases. The simultaneous administration of fenofibrate and T09 did not show additive effects on the mRNA expression and activity of the desaturases. Therefore, the results indicate a necessary sophisticated interaction of all these factors to produce the physiological effects.     

0Cr18Ni9材料紧固件制作工艺探讨

0Cr1 8 Ni9材料高强度系列紧固件力学性能要求很高 ,要求采用超低温奥氏体不锈钢制作 ,固溶状态使用。一般生产工艺根本无法达到技术条件要求。我们通过反复试验 ,力求通过强化工艺使该材料达到要求的力学性能 ,现已摸索出两种强化工艺 ,可以达到该材料技术要求的强度 ,从而解决该系列紧固件制造的难题。     

R9E动车轮E级热处理工艺试验及应用

根据BS5892——1992标准中R9E动车轮E级热处理的要求，研究了加热温度、加热时间、冷却介质等对动车轮整体力学性能的影响。通过工艺试验，确定了动车轮E级热处理工艺规程，满足了BS5892—1992标准的要求。     

认清形势 振奋精神全面完成化工“八五”计划的各项任务

总结回顾了１９９４年中国化学工业的改革及发展现状，提出了１９９５年化工生产建设的目标及在化工行业改革方面的四项试点工作，强调了编制“九五”计划的重要性。     

Structure-activity relationship studies on the immune stimulatory effects of base-modified CpG toll-like receptor 9 agonists

Synthetic oligodeoxynucleotides containing unmethylated deoxycytidylyl-deoxyguanosine dinucleotide (CpG) motifs are able to stimulate potent immune responses through a signaling pathway involving Toll-like receptor 9 (TLR9). We have investigated the structure-activity relationship (SAR) of base-modified CpG oligonucleotides with TLR9 by measuring TLR9 activation by 20-mer oligonucleotides having just a single human recognition motif (5'-GTCGTT-3') in functional cell-based TLR9 assays. Substitution of guanine by hypoxanthine and 6-thioguanine resulted in activity similar to the unmodified parent molecule, whereas purine, 2-aminopurine, 2,6-diaminopurine, and 8-oxo-7,8-dihydroguanine substitution resulted in approximately 40-60 % reduction in activity, and 7-deazaguanine substitution led to the strongest (80 %) reduction in TLR9 stimulation. Furthermore, none of the investigated modifications at C5 and N4 of cytosine were well tolerated with respect to human TLR9 stimulation. Our results are compatible with a SAR model in which guanine is recognized by the Hoogsteen site, and C5 is most critical for recognition of cytosine. In addition, we found significant species-specific differences between human and murine TLR9 recognition, which demonstrates the importance of choosing appropriate assay systems for SAR studies.     

Application of mushy/semi-solid joining—Part 3

A process to join glass or stone onto base metal alloys is proposed. The process characteristics allow using various kinds of glasses or stones, such as craft glass, beads, tile, amethyst, agate and hematite with different shapes and sizes. The process utilizes excellent and active join ability of mushy or semi-solid alloy’s properties. In this study, the mechanism of the joining was investigated and some applications were showed. The process itself has several useful properties like: (1) easy-to-operate, (2) ability to get good joining condition, and (3) applicability to a continuous production system. Through the study, it is found that the mushy joining is a useful and valuable manufacturing method for developing and manufacturing glass/metal or stone/metal composites. The mushy joining process is different from the existing cloisonné and enameling process.